This is automatically enforced if fast mode is turned on.
Each player is given 2 stall actions per game where they can choose to take 1 action and end turn. This alleviates situations where you need an odd number of actions to set up a combination play or sequence, without being unfairly penalised by the fast mode mechanism.
Some examples:
During the Solar Phase, instead of increasing a global parameter during the world government terraforming step, select a parameter to place 5 MC on.
The next player to raise that parameter will receive a rebate of all MC accumulated on that parameter, which then has its silver cube MC value reset to 0.
If the value of silver cubes ever reaches the cost of its related standard project, that global parameter will be neutrally increased by the World Government.
Global events that raise parameters will clear any existing silver cube MC on that parameter.
This variant gives each player the Merger prelude available for selection after drafting. If they have already drafted Merger, they will get a 5th prelude from the deck instead.
This is an unofficial house rule that prevents players with multiple trade fleets from doing 2 trades in one turn. With this setting, each player may only do 1 trade per turn.
This is an unofficial house rule that allows players to build a colony on any available colony tile, if they do not already have a colony there.
Example: In a 4-player game, the first 3 players build colonies on Pluto on their first turn. The 4th player can still build a colony on Pluto during their first turn as they do not have a colony there yet.